ALGITES. 5 



The genus Chondrites is suggestive of supposed affinity with 

 Chondria, but the definition given by Brongniart 1 shows that it 

 was intended for the reception of forms with cylindrical branches. 

 In Schimper's " Traite de Paleontologie " the genus Chondrides* 

 is defined as comprising fossils with cylindrical fronds, often 

 repeatedly dichotomising, and possessing characters united in 

 Chondria and Furcellaria among living alga3. Those fossil algre 

 with flattened fronds are referred to the genus Spharococcides, a 

 name previously used by Sternberg as Sphcerococcites, and defined 

 by him as follows: " Frons subcoriacea, plana dichotoma vel 

 pinnata aut filiformis." 3 



Schimper includes this genus in the Floridea, and considerably 

 extends Sternberg's definition. 



Seeing that the specimens from the Wealden rocks do not conform 

 exactly to any of these definitions, and that such terms are, to some 

 extent, associated with definite genera of recent seaweeds, it is 

 better to make use of a wider designation, such as Algites. 



There are some few fossils previously described from Mesozoic 

 and Tertiary rocks, to which Algites valdensis shows a certain 

 amount of resemblance. 



Under the name Chondrides dolichophyllus Squinabol* has 

 described a specimen from Liguria which has a general habit 

 similar to the Wealden species, but differs in the narrower and 

 longer branches. Heer's figure of Gyrophyllites Theolaldi, Hr., 

 in the Foss. fl. Helvet, 5 shows an analogous type of plant, but 

 the generic name which he adopts was instituted by Glocker 6 in 

 1841 for a Cretaceous fossil which resembles the genus Caulerpa 

 much more strongly than the flattened branching algae with which 

 the present specimens agree. From the Jurassic rocks of East 

 Yorkshire Leckenby 7 has described a supposed alga, Fucoides 

 erectus, which slightly resembles Algites valdensis ; but the 

 presence of a midrib and the delicate nature of the lateral parts 

 of the branches are much more suggestive of Hepatic affinities. 



1 Tableau, p. 9. See also Prodrome, p. 20, where the older name Gigartinites 

 is defined. 



2 Trait, pal. veg. vol. i. p. 168. 



3 Flor. Vorwelt, fasc. vii. p. 28. 



4 Contrib. Fl. foss. Liguria, vol. i. Tav. B, p. 11. 

 6 PI. xlv. fig. 1. 



6 Nova Acta Ac. Caes. Leop.-Car. vol. xix. supp. ii. p. 322. 



7 Quart. Journ. Geol. Soc. vol. xx. p. 74, pi. xi. figs. 3a and 3b. 



